The surest way to know that LeBron James-to-Miami is a done deal before LeBron’s official announcement?

If Miami trades away Michael Beasley to create even more salary-cap space before the show starts.

As of noon Thursday, Miami did not have a trade taker for Beasley, after numerous sources said that the Heat – as they’ve been doing for weeks – continued to shop 2008’s No. 2 overall pick with vigor for much of Wednesday.

Yet sources say that a four-team trade scenario was hatched on the eve of LeBron’s hour-long “Decision” special on ESPN that includes Charlotte and Houston and would enable the Raptors to bring them back an asset or two in the wake of Chris Bosh’s departure but also avoid taking back Beasley. Which is believed to be the only sort of sign-and-trade that Toronto would consider.

The Heat and Raptors engaged in discussions for several hours after Bosh and Dwyane Wade announced that they committing to Miami in a package about the various sign-and-trade options. Discussions were serious enough Wednesday night, according to two sources, that Heat officials told Beasley to start preparing to relocate.

One source with knowledge of Toronto’s thinking, however, insists that the four-team trade – which would require Houston to send at least $3.1 million in salary to the Raptors -- is “not happening.” Toronto continues to convey the message that it is a reluctant partner in any deal that makes Bosh’s departure more lucrative.

If the Raptors ultimately consent to a sign-and-trade, Bosh would be able to sign a six-year max deal with the Heat worth nearly $130 million and LeBron and D-Wade would score max deals, too. Toronto, meanwhile, would come away with a very big trade exception and presumably at least one first-round pick … possibly its 2011 first-rounder that was previously dealt to Miami.

But Miami’s lack of options -- with only Beasley and Mario Chalmers officially on the roster on Decision Day – and concerns about Beasley’s off-the-court issues are undeniable stumbling blocks when it comes to any deal.

Such is Miami’s fortune these days, though, that it can offer near-maxes to the three Team USA buddies even without finding a new home for Beasley. The Heat found that out Wednesday night, along with the rest of a grumbling league, when the NBA announced that the salary cap next season will be nearly $2 million higher than anticipated: $58 million as opposed to $56.1 million.

The latest estimates say that James, Wade and Bosh could all sign deals with a first-year salary just under $1 million less than the max if the Heat make no more moves before James’ makes his intentions official. Miami would have to fill out the rest of its roster with minimum-salary players, but the trio’s financial sacrifice would have been more unrealistic if the cap figure didn’t rise. Factor in the lack of state income tax in Florida and the sacrifice shrinks further.